Spiral wound gasket



Jan. 14, 1964 w. R. PRICE SPIRAL wouND GASKET Filed Aug. 4, 1961 ATTORNEY nite States atent M' This invention reiates to spiral wound gaskets and has for an object to provide a gasket of the above type which is corrosion resistant and has improved seaiing qualities.

The invention embodies specifically a spiral wound gasket ot the type shown in the Bohmer Patent No. 1,829,709 which comprises a spiral wound beaded metal strip having a filler of iibrous material such as asbestos interposed between adjacent convolutions. When such a gasket is used to seal a pipe flange, for example, the inner convolution of the metal strip is exposed to the uid within the pipe. if the duid is corrosive to the metal of the gasket it is difficult to maintain a. proper seal tor any extended period of time. On the other hand an inner protective sealing ring of corrosion resistant material usually faiis to maintain a suiiiciently tight seal to prevent vapor from contacting the metal of the gasket.

The present invention overcomes these diiculties by producing a sealing ring of corrosion resistant material which covers all exposed surfaces of the metal and is bound thereto in a manner to effect a permanent seal and protection for ali metal parts of the gasket.

The invention will be better understood from the following description, taken in connection with the accompanying drawing in which a specific embodiment has been set forth for purposes of illustration.

in the drawing:

FIG. 1 is an elevation of a gasket embodying the invention with parts broken away for clarity;

iiG. 2 is a section taken on the line 2-2 of FIG. 1 but on a much larger scale;

FIG. 3 is a partial sectional showing the gasket in position in a pipe joint; and

FG. 4 is a section of a portion of a gasket illustrating a further embodiment of the invention.

Referring to the drawing more in detail the invention is shown as embodied in a gasket composed of a spiral wound metal strip 1t? having a central longitudinal bead 1i and having strips 12 of a iiller such as asbestos strips interposed between adiacent convolutions and spirally Wound therewith as shown in the Bohmer patent above nentioned. lf high corrosion resistance is required the strips 12 may be made of a corrosion resistant material such as Teflon, polytetratluoroethylene.

entire gasket is enclosed in an envelope of Telion comprising an inner sealing ring ist, side t'ilrns i5 covering the edges of the metal strips and an outer layer 15 covering the outer peripheral surface of the gasket. The inner sealing ring 14 is solid in section except for an annular recess i7 extending from its inner periphery and dividing the ring portion into a pair of flanges 18.

The gasket above described is fuliy protected from contact With corrosive vapors during shipment, storage and installation by the Teiion envelope. When the gasket is instalied between end anges 2li of a pair of pipe sections 2i as shown in FiG. 3 and held under pressure by bolts 22 the Teflon of the iiim 15 is forced between adjacent convolutions of the metal strip 1i? as indicated at 23 to seal the spaces between such convolutions. The

Patented Jari. i4, i854 anges 29 compress the ring portion i4 of the envelope and the duid pressure within the pipe 21 enters the annular recess 17 and causes the flanges 13 to maintain a tight seal with the surfaces of the anges 2% thereby preventing the corrosive duid within the pipes 21 from contacting any portion of the metal strip it) of the gasket.

The protective envelope above described is preferably formed in one piece by casting the same around the gasket or by dipping or in any other convenient manner. When so formed the sealing ring 14 is securely aiixed to the gasket and cannot be removed either in shipment or during use. The ring portion 14 normally prevents any leakage of vapors along the pipe flanges 25.9. However, in the event of any such leakage the vapors are prevented by the portions 23 of the envelope from coming in contact with any of the side surfaces or" the metal strip 1d.

The protective envelope has been described as made of Teflon because of the inert properties ot this material. Other plastic materials may be used however according to the nature of the fluids with which the gasket is to be used.

In the embodiment of FIG. 4 a spiral wound gasket is shown comprising a metal strip 1i? having a longitudinal bead 11 and spiraily wound with intervening convolutions of an asbestos strip 12 as in the embodiment above described. A separate inner ring of Teon is provided with an external bead 25 seating in the inner groove 26 or" the spiral wound gasket. The ring 24 is similar to the ring 14 above described and is provided with an inner slot or recess 27 forming opposing iianges 28.

In this form the ring 24 is made somewhat thicker than the spiral Wound metal strips Si@ so that it is placed under compression when in use. The slot or opening 27 causes the pressure ofthe internal fluids to hold the flanges 28 in rm pressure engagement with the opposed metal surfaces so as to maintain an eective seal. This embodiment may be useful in instance where the complete enclosure of the metal strips is found to be unnecessary.

What is claimed is:

1. A gasket having corrosion resistant properties comprising a spiral Wound metal strip in the form of a plurality of convolutions with a ller of non-metallic material disposed between adjacent convolutions, and a onepiece envelope of molded plastic corrosion-resistant material enclosing said gasket and consisting of an inner sealing ring within the inner periphery of the gasket, and a film disposed over the two sides thereof in a unitary structure, said inner sealing ring having an annular groove extending from the inner periphery thereof to form a pair or" flanges terminating at the innermost periphery of said gasket, said flanges adapted to be brought into sealing contact with a sealing surface by reason of fluid pressure exerted from the innermost periphery of said gasket.

2. A gasket as set forth in claim 1 in which said envelope is composed of polytetrauoroethylene.

References Qited in the tile of this patent UNlTED STATES PATENTS 

1. A GASKET HAVING CORROSION RESISTANT PROPERTIES COMPRISING A SPIRAL WOUND METAL STRIP IN THE FORM OF A PLURALITY OF CONVOLUTIONS WITH A FILLER OF NON-METALLIC MATERIAL DISPOSED BETWEEN ADJACENT CONVOLUTIONS, AND A ONEPIECE ENVELOPE OF MOLDED PLASTIC CORROSION-RESISTANT MATERIAL ENCLOSING SAID GASKET AND CONSISTING OF AN INNER SEALING RING WITHIN THE INNER PERIPHERY OF THE GASKET, AND A FILM DISPOSED OVER THE TWO SIDES THEREOF IN A UNITARY STRUCTURE, SAID INNER SEALING RING HAVING AN ANNULAR GROOVE EXTENDING FROM THE INNER PERIPHERY THEREOF TO FORM A PAIR OF FLANGES TERMINATING AT THE INNERMOST PERIPHERY OF SAID GASKET, SAID FLANGES ADAPTED TO BE BROUGHT INTO SEALING CONTACT WITH A SEALING SURFACE BY REASON OF FLUID PRESSURE EXERTED FROM THE INNERMOST PERIPHERY OF SAID GASKET. 